diff options
| author | Dominik Brodowski <linux@dominikbrodowski.net> | 2018-02-14 18:59:23 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-02-17 11:14:33 +0100 |
| commit | 9e809d15d6b692fa061d74be7aaab1c79f6784b8 (patch) | |
| tree | 950462832b5f0153c51a9a72ee1ebc793c91006c /arch/x86/entry/calling.h | |
| parent | 42ca8082e260dcfd8afa2afa6ec1940b9d41724c (diff) | |
x86/entry: Reduce the code footprint of the 'idtentry' macro
Play a little trick in the generic PUSH_AND_CLEAR_REGS macro
to insert the GP registers "above" the original return address.
This allows us to (re-)insert the macro in error_entry() and
paranoid_entry() and to remove it from the idtentry macro. This
reduces the static footprint significantly:
text data bss dec hex filename
24307 0 0 24307 5ef3 entry_64.o-orig
20987 0 0 20987 51fb entry_64.o
Co-developed-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180214175924.23065-2-linux@dominikbrodowski.net
[ Small tweaks to comments. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/entry/calling.h')
| -rw-r--r-- | arch/x86/entry/calling.h | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h index dce7092ab24a..196b6103edf6 100644 --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -97,7 +97,7 @@ For 32-bit we have the following conventions - kernel is built with #define SIZEOF_PTREGS 21*8 -.macro PUSH_AND_CLEAR_REGS rdx=%rdx rax=%rax +.macro PUSH_AND_CLEAR_REGS rdx=%rdx rax=%rax save_ret=0 /* * Push registers and sanitize registers of values that a * speculation attack might otherwise want to exploit. The @@ -105,8 +105,14 @@ For 32-bit we have the following conventions - kernel is built with * could be put to use in a speculative execution gadget. * Interleave XOR with PUSH for better uop scheduling: */ + .if \save_ret + pushq %rsi /* pt_regs->si */ + movq 8(%rsp), %rsi /* temporarily store the return address in %rsi */ + movq %rdi, 8(%rsp) /* pt_regs->di (overwriting original return address) */ + .else pushq %rdi /* pt_regs->di */ pushq %rsi /* pt_regs->si */ + .endif pushq \rdx /* pt_regs->dx */ pushq %rcx /* pt_regs->cx */ pushq \rax /* pt_regs->ax */ @@ -131,6 +137,9 @@ For 32-bit we have the following conventions - kernel is built with pushq %r15 /* pt_regs->r15 */ xorq %r15, %r15 /* nospec r15*/ UNWIND_HINT_REGS + .if \save_ret + pushq %rsi /* return address on top of stack */ + .endif .endm .macro POP_REGS pop_rdi=1 skip_r11rcx=0 |